1. Field of the Invention
The invention is concerned with a connector for an optical fiber cable wherein a bare end of an optical fiber is mounted with an adhesive, which connector permits the mounted optical fiber to be connected optically, e.g, to another optical fiber or to an optoelectronic device.
2. Description of the Related Art
In most optical fiber connectors, an epoxy resin adhesive is employed to mount the end of the optical fiber. Detailed instructions for doing so are given in "Field Termination Instruction Manual for Dorran.TM. . . . Field Mountable Connectors," December 1988, 3M Fiber Optic Products. To do so, the epoxy resin adhesive is mixed and loaded into a syringe by which it is injected into the connector. After coating the outer jacket of the optical fiber cable with a thin layer of the epoxy composition, the epoxy-containing connector is threaded onto the fiber, the connector is crimped onto the outer jacket, and a load adapter and strain relief boot are applied. The resulting assembly is inserted into a port of an oven to cure the epoxy resin adhesive, followed by scoring and breaking off the fiber and polishing until the end of the fiber and the cured epoxy resin are flush with the end face of the connector.
A number of patents concern other types of optical fiber connectors wherein a base optical fiber is mounted by a curable adhesive such as an epoxy resin composition. For example, see U.S. Pat. No. 4,476,194 (Rasmussen) which employs an epoxy adhesive or a light-curing adhesive. See also U.S. Pat. No. 4,713,523 (MacDonald) which concerns apparatus that is said to improve the control of the heating of the epoxy composition during cure.
U.S. Pat. No. 4,588,256 (Onstott et al.) concerns an optical fiber connector that preferably employs a hot-melt adhesive instead of a curable adhesive. Referring to FIG. 1, the hot-melt adhesive is injection loaded into a tubular member 24 of an optical fiber mounting means 16 which is placed in a heatable jig to liquify the hot-melt adhesive and allow insertion of an optical fiber. The hot-melt adhesive is not identified, and the Onstott connector has not been marketed.
U.S. Pat. No. 4,812,006 (Osborn et al.) says that the use of an epoxy adhesive to retain an optical fiber cable in a connector is messy and requires time for the adhesive to cure. Osborn also says that another approach which has been suggested is to use a soft plastic body surrounding the cable and a metal tube covering the plastic body. Osborn avoids the use of any adhesive by employing a mechanical connector wherein the end of an optical fiber fits snugly in a bore. Unfortunately, any connector that employs only mechanical means to mount an optical fiber would not be suitable for uses requiring precise positioning of the end of the fiber.
The term "optical fiber connector" has also been used to describe devices for forming butt joints or splices of optical fibers. See, for example, U.S. Pat. Nos. 4,729,619 (Blomgren); 4,812,008 (Tokumaru et al.); and 4,784,457 (Finzel). The Blomgren patent points out that in such devices, index matching materials enable the splicing of optical fibers which have irregular ends or which are not butted together precisely. However, the term "optical fiber connector," as used in the present application, does not encompass such devices, but only a device that can be mechanically fastened to another device to effect an optical connection between the two devices.